Production process of 9SiCr cold-rolled wide plate coil

Abstract

The application provides a production process of a 9SiCr cold-rolled wide-width plate coil, which comprises the following steps: subjecting a 9SiCr hot-rolled plate coil to first annealing, pickling, spheroidizing annealing, rolling and second annealing; the first annealing comprises a first temperature rising section, a second temperature rising section, a first temperature holding section, a third temperature rising section, a second temperature holding section, a first cooling and a second cooling; the temperature of the first temperature holding section in the first annealing process is 380-420 DEG C; and the width of the 9SiCr cold-rolled wide-width plate coil is above 900 mm. In the application, the 9SiCr hot-rolled plate coil is firstly subjected to first annealing to soften and remove stress, then subjected to pickling, and then subjected to spheroidizing annealing; the annealed steel coil is subjected to rolling, and finally subjected to second annealing to form a cold-rolled finished product coil. The application adopts a wide-width plate coil to produce a high-quality cold-rolled 9SiCr cold-rolled plate coil, and has the characteristics of high production efficiency, low production cost and stable process.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of steel smelting, in particular to a production process of 9SiCr cold-rolled wide-width plate coil. BACKGROUND

[0002] 9SiCr is a kind of low-alloy tool steel, also belongs to low-carbon high-hardness steel. It is composed of iron, carbon, silicon and chromium and other elements, and is obtained through special heat treatment process. This kind of steel has the characteristics of high hardness, good toughness, strong wear resistance, high impact resistance and good heat fatigue resistance. 9SiCr steel also has excellent cutting performance and wear resistance, which can greatly improve the service life of tools and dies. Due to its high hardenability and hardenability, as well as high tempering stability, 9SiCr is suitable for grading quenching or isothermal quenching.

[0003] 9SiCr steel has a long application history, and is mainly used to manufacture machine tool accessories and cold working dies, such as printing dies, gear hobbing dies, wire drawing plates and cold punching dies. In recent years, 9SiCr is gradually applied to heavy-duty dies, and some are used to replace Cr12 steel.

[0004] There are two difficulties in the cold rolling production process of this material:

[0005] One is that pickling is difficult, and the iron oxide scale of the steel coil is relatively easy to remove when the hot-rolled coil is directly pickled in the pickling process of this steel grade, but due to the high strength and poor plate shape of the steel coil, uncoiling is prone to belt breaking and scratching, and pickling is very difficult. The pickling speed is 10m / min-30m / min, and the pickling efficiency is low. After annealing and spheroidizing, the pickling can reduce the strength of the steel coil, and the pickling difficulty is relatively low. But the surface iron oxide scale is reduced to iron scale by hydrogen in the cover furnace, and the pickling needs to be strictly controlled at low speed. And it is difficult to remove the reduced iron scale covered on the surface layer during pickling, and the residual oxides under the iron scale are easy to cause the oxide to be pressed into the subsequent cold rolling. Even in the environment of high-temperature annealing with inert gas protection, the oxygen elements in the iron oxide scale will also diffuse and react with the carbon in the matrix, causing the iron oxide scale to be reduced to iron scale which is difficult to pickle. And the oxygen elements migrating and diffusing will further oxidize the surface layer of the matrix, causing the surface layer of the matrix to be oxidized and the surface decarburization layer to be generated. The pickling methods currently used in the industry all have disadvantages, so the pickling process path of 9SiCr needs to be optimized.

[0006] The second is that the traditional production process of 9SiCr tool steel cold-rolled coil is produced by single stand + narrow strip (width ≤500mm), and there is no single stand + wide-width plate coil (width >900mm) form. When the narrow strip is added to the single stand mode, the reduction rate is generally less than 25%, and the reduction rate is increased. It is easy to break the belt, and there are problems of low cold rolling production efficiency, difficult control of steel coil plate difference and large edge drop.

[0007] CONTENT

[0008] The present application is made in view of the above problems, and aims to provide a production process of 9SiCr cold-rolled wide-width plate coil, which can

[0009] Specifically, the present application provides a production process of 9SiCr cold-rolled wide-width plate coil, comprising the following steps:

[0010] The 9SiCr hot-rolled plate coil is subjected to first annealing, pickling, spheroidizing annealing, rolling and second annealing;

[0011] The first annealing comprises a first temperature rising section, a second temperature rising section, a first temperature holding section, a third temperature rising section, a second temperature holding section, a first cooling section and a second cooling section;

[0012] The temperature of the first temperature holding section in the first annealing process is 380-420℃;

[0013] The width of the 9SiCr cold-rolled wide-width plate coil is above 900mm.

[0014] According to one of the technical solutions of the present application, at least the following beneficial effects are achieved:

[0015] In the present application, the 9SiCr hot-rolled plate coil is first subjected to first annealing to soften and remove stress, then subjected to pickling, and then subjected to spheroidizing annealing. The annealed steel coil is subjected to rolling, and finally subjected to second annealing to form a cold-rolled finished coil. The present application uses wide-width plate coil to produce high-quality cold-rolled 9SiCr cold-rolled plate coil, and has the characteristics of high production efficiency, low production cost and stable process.

[0016] According to some embodiments of the present application, the first temperature rising section in the first annealing process has a rate of 350-450℃ / h.

[0017] According to some embodiments of the present application, the first temperature rising section in the first annealing process has a time of 0.4-0.6h.

[0018] According to some embodiments of the present application, the first temperature rising section in the first annealing process has a final temperature of 190-210℃.

[0019] According to some embodiments of the present application, the second temperature rising section in the first annealing process has a rate of 60-80℃ / h.

[0020] According to some embodiments of the present application, the second temperature rising section in the first annealing process has a final temperature of 380-420℃.

[0021] According to some embodiments of the present application, the first temperature holding section in the first annealing process has a time of 3-5h.

[0022] According to some embodiments of this application, the heating rate of the third stage during the first annealing process is 60℃ / h to 80℃ / h.

[0023] According to some embodiments of this application, the final temperature of the third stage of heating during the first annealing process is 500℃~660℃.

[0024] According to some embodiments of this application, the temperature of the second stage of heat preservation during the first annealing process is 500℃~660℃.

[0025] According to some embodiments of this application, the second holding time during the first annealing process is 10h to 20h.

[0026] According to some embodiments of this application, the final temperature of the first cooling during the first annealing process is 380°C to 420°C.

[0027] According to some embodiments of this application, the first cooling method during the first annealing process is air cooling.

[0028] According to some embodiments of this application, the final temperature of the second cooling during the first annealing process is 90°C to 100°C.

[0029] According to some embodiments of this application, the second cooling method during the first annealing process is water cooling.

[0030] According to some embodiments of this application, the pickling solution is hydrochloric acid.

[0031] According to some embodiments of this application, the hydrochloric acid has a mass fraction of 12% to 18%.

[0032] According to some embodiments of this application, the temperature of the pickling solution is 70°C to 90°C.

[0033] According to some embodiments of this application, the pickling rate is 30 m / min to 160 m / min.

[0034] According to some embodiments of this application, the pickling also includes water washing.

[0035] According to some embodiments of this application, the temperature of the water wash is 60°C to 80°C.

[0036] According to some embodiments of this application, the water washing is followed by drying.

[0037] According to some embodiments of this application, the drying is hot air drying.

[0038] According to some embodiments of this application, the temperature of the hot air is 100°C to 140°C.

[0039] According to some embodiments of the present application, the spheroidizing annealing comprises a first temperature rising, a second temperature rising, a first temperature holding, a third temperature rising, a second temperature holding, a first cooling, a second cooling and a third cooling.

[0040] According to some embodiments of the present application, the rate of the first temperature rising in the spheroidizing annealing process is 350℃ / h-450℃ / h.

[0041] According to some embodiments of the present application, the time of the first temperature rising in the spheroidizing annealing process is 0.4h-0.6h.

[0042] According to some embodiments of the present application, the final temperature of the first temperature rising in the spheroidizing annealing process is 190℃-210℃.

[0043] According to some embodiments of the present application, the rate of the second temperature rising in the spheroidizing annealing process is 60℃ / h-80℃ / h.

[0044] According to some embodiments of the present application, the final temperature of the second temperature rising in the spheroidizing annealing process is 380℃-420℃.

[0045] According to some embodiments of the present application, the temperature of the first temperature holding in the spheroidizing annealing process is 380℃-420℃.

[0046] According to some embodiments of the present application, the time of the first temperature holding in the spheroidizing annealing process is 3h-5h.

[0047] According to some embodiments of the present application, the rate of the third temperature rising in the spheroidizing annealing process is 60℃ / h-80℃ / h.

[0048] According to some embodiments of the present application, the final temperature of the third temperature rising in the spheroidizing annealing process is 700℃-800℃.

[0049] According to some embodiments of the present application, the temperature of the second temperature holding in the spheroidizing annealing process is 700℃-800℃.

[0050] According to some embodiments of the present application, the time of the second temperature holding in the spheroidizing annealing process is 10h-20h.

[0051] According to some embodiments of the present application, the final temperature of the first cooling in the spheroidizing annealing process is 580℃-620℃.

[0052] According to some embodiments of the present application, the final temperature of the second cooling in the spheroidizing annealing process is 380℃-420℃.

[0053] According to some embodiments of the present application, the third cooling in the spheroidizing annealing process is air cooling.

[0054] According to some embodiments of the present application, the final temperature of the third cooling in the spheroidizing annealing process is 90℃-100℃.

[0055] According to some embodiments of the present application, the third cooling in the spheroidizing annealing process is water cooling.

[0056] According to some embodiments of the present application, the rolling is performed by a wide plate single stand cold rolling mill.

[0057] According to some embodiments of the present application, the rolling force of the cold rolling is set to 800TON-1000TON.

[0058] According to some embodiments of the present application, the tension of the cold rolling mill is 150KN-240KN.

[0059] According to some embodiments of the present application, the cold rolling work roll adopts a rough roll rolling.

[0060] According to some embodiments of the present application, the cold rolling reduction is 30%-40%.

[0061] According to some embodiments of the present application, the rolling speed is 200m / min-300m / min.

[0062] According to some embodiments of the present application, the rolling adopts a roll shifting mode rolling.

[0063] According to some embodiments of the present application, the roll shifting value is 30mm-90mm.

[0064] According to some embodiments of the present application, the second annealing includes a first temperature rising, a second temperature rising, a first temperature holding, a third temperature rising, a second temperature holding, a first cooling, a second cooling and a third cooling.

[0065] According to some embodiments of the present application, the first temperature rising in the second annealing process has a rate of 350℃ / h-450℃ / h.

[0066] According to some embodiments of the present application, the first temperature rising in the second annealing process has a time of 0.4h-0.6h.

[0067] According to some embodiments of the present application, the first temperature rising in the second annealing process has a final temperature of 190℃-210℃.

[0068] According to some embodiments of the present application, the second temperature rising in the second annealing process has a rate of 40℃ / h-80℃ / h.

[0069] According to some embodiments of the present application, the final temperature of the second temperature rising in the second annealing process is 380-420℃.

[0070] According to some embodiments of the present application, the temperature of the first holding in the second annealing process is 380-420℃.

[0071] According to some embodiments of the present application, the time of the first holding in the second annealing process is 3-5h.

[0072] According to some embodiments of the present application, the rate of the third temperature rising in the second annealing process is 40-80℃ / h.

[0073] According to some embodiments of the present application, the final temperature of the third temperature rising in the second annealing process is 700-800℃.

[0074] According to some embodiments of the present application, the temperature of the second holding in the second annealing process is 700-800℃.

[0075] According to some embodiments of the present application, the time of the second holding in the second annealing process is 10-20h.

[0076] According to some embodiments of the present application, the final temperature of the first cooling in the second annealing process is 580-620℃.

[0077] According to some embodiments of the present application, the final temperature of the second cooling in the second annealing process is 380-420℃.

[0078] According to some embodiments of the present application, the mode of the second cooling in the second annealing process is air cooling.

[0079] According to some embodiments of the present application, the final temperature of the third cooling in the second annealing process is 90-100℃.

[0080] According to some embodiments of the present application, the mode of the third cooling in the second annealing process is water cooling.

[0081] According to some embodiments of the present application, the 9SiCr cold-rolled wide plate coil is composed of the following mass fractions of elements:

[0082] C 0.9-0.95%, Si 1.3-1.5%, Mn 0.4-0.6%, Cr 1.0-1.2%, and the balance of Fe and indispensable residual or impurity elements.

[0083] According to some embodiments of the present application, the thickness of the 9SiCr hot-rolled plate coil is 2.5mm-3.5mm.

[0084] According to some embodiments of the present application, the width of the 9SiCr hot-rolled plate coil is 900mm-1500mm.

[0085] According to some embodiments of the present application, the thickness of the 9SiCr cold-rolled wide plate coil is 1.5mm-1.8mm.

[0086] According to some embodiments of the present application, the width of the 9SiCr cold-rolled wide plate coil is 900mm-1500mm.

[0087] According to some embodiments of the present application, the thickness precision of the 9SiCr cold-rolled wide plate coil is -10μm-10μm.

[0088] According to some embodiments of the present application, the convexity C40 of the 9SiCr cold-rolled wide plate coil is within 6μm. BRIEF DESCRIPTION OF DRAWINGS

[0089] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on the drawings shown.

[0090] Figure 1 It is the cross-sectional view after high-temperature annealing in Comparative Example 1 (the scale is 10μm).

[0091] Figure 2 It is the cross-sectional view after the first annealing in Embodiment 1 of the present application (the scale is 10μm).

[0092] Figure 3 It is the surface defect view after pickling in the present application.

[0093] Figure 4 It is the surface defect view after cold rolling in the present application.

[0094] Figure 5 It is the surface defect view of the steel after cold rolling in Comparative Example 1.

[0095] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0096] In order to make the purposes, technical solutions, and advantages of the present application clearer, the present application will be described and illustrated in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present application.

[0097] Obviously, the following description is only some examples or embodiments of the present application, and for those of ordinary skill in the art, the present application can also be applied to other similar scenarios without creative efforts. In addition, it can be understood that although the efforts made in the development process can be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacture or production changes based on the technical content disclosed in the present application are only routine technical means and should not be understood as insufficient disclosure of the content disclosed in the present application.

[0098] However, there will be cases of omitting unnecessary detailed descriptions. For example, there are cases of omitting detailed descriptions of well-known matters, repeated descriptions of practically identical structures. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided in order for those skilled in the art to fully understand the present application and is not intended to limit the subject matter recited in the claims.

[0099] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions if not specifically stated.

[0100] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions if not specifically stated.

[0101] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0102] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0103] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0104] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0105] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0106] If not specifically stated otherwise, the term "or" in this application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0107] The production process of the 9SiCr wide plate coil in this application includes the following steps:

[0108] The 9SiCr hot-rolled plate coil is subjected to first annealing, pickling, spheroidizing annealing, rolling, and second annealing;

[0109] According to some embodiments of the application, the process parameters of the first annealing are as follows:

[0110] The coil is heated from room temperature (20-25°C) to 200°C at a free heating rate, then heated to 400°C at a heating rate of 60-80°C / h and held for 4h;

[0111] Then heated to 500-660°C at a rate of 60-80°C / h and held for 10-20h, and after the holding is completed, the air is replaced and cooled to 400°C, and then water is used to cool to 100°C and the furnace is discharged.

[0112] In this way, the problems of difficult pickling, poor pickling effect, etc. are solved.

[0113] 9SiCr tool steel is difficult to pickle: this steel grade has high carbon and silicon content, high material strength and brittleness, high hot rolling load, and very thick oxide on the surface of the coil. When pickling at a speed much lower than that of other high-carbon steels, it needs to be pickled two to three times to be clean. When the speed is faster or the number of times is less, the surface is not clean and there are residual pits.

[0114] There are two kinds of conventional material pickling process paths, one is to pickle after annealing the hot coil, and the other is to pickle the hot coil directly.

[0115] The former can reduce the strength of the coil, but the surface iron oxide scale is reduced to iron scale by hydrogen in the hood furnace, which is difficult to remove during pickling, and the residual oxide under the iron scale is easy to cause the oxide to press into the subsequent cold rolling; the latter is relatively easy to remove the iron oxide scale, but the coil has high strength, poor shape, and is easy to break and scratch during uncoiling, making it very difficult to pickling. The production preparation for pickling is too long, and the efficiency is low. Therefore, the appropriate process path for pickling of such steel grade raw coil is to use soft annealing (i.e. first annealing) at a lower temperature to inhibit the reduction of oxide.

[0116] According to some embodiments of the application, the process parameters of the pickling process are as follows:

[0117] After the low temperature annealing, the steel coil is reduced from 1400 MPa tensile strength to 900 MPa, and the steel coil is successfully passed through the strip. Under the condition of reducing the concentration of the regenerated acid and the water temperature, the normal pickling can be realized, the quality is ensured, and the pickling cost is saved.

[0118] High temperature annealing (parameters see Comparative Example 1) cross section Figure 1 The surface oxide is reduced to sponge iron by hydrogen, and is difficult to be removed during pickling (see Figure 1 ). The cross section result after the first annealing (Example 1) is shown in Figure 2 The surface oxide is not basically reduced, and is easy to be removed during pickling.

[0119] Hydrochloric acid pickling, the mass fraction of hydrochloric acid is 12% to 18%, the temperature of hydrochloric acid is 70℃ to 90℃, and the pickling speed is 30m / min to 160m / min;

[0120] After hydrochloric acid pickling, water rinsing, the rinsing temperature is 60℃ to 80℃;

[0121] The strip steel after rinsing is dried by hot air, and the temperature of hot air is 110℃ to 120℃.

[0122] According to some embodiments of the application, the process parameters of the spheroidizing annealing process are as follows:

[0123] The steel coil is heated from room temperature (20℃ to 25℃) to 200℃ freely, then heated to 400℃ at a heating rate of 60℃ / h and kept for 4h;

[0124] Then heated to 700℃ to 800℃ at a heating rate of 60℃ / h, and kept for 10h to 20h;

[0125] After the end of keeping, the furnace is cooled to about 600℃, then air is replaced to cool to 400℃, and then water is replaced to cool to 100℃ and the furnace is discharged.

[0126] According to some embodiments of the application, the process parameters of the rolling are as follows:

[0127] The process parameters are set according to the basic yield strength of 700 to 800 MPa during rolling, the rolling force and tension of the material during rolling are stable, and the shape control is good. The finished product thickness is uniformly distributed, the thickness difference fluctuation is small, the thickness precision is ±10μm, and the crown C40 is within 6μm.

[0128] The rolling is cold rolling;

[0129] The cold rolling is produced by a wide plate single stand cold rolling unit, the cold rolling rolling force is 800 TON-1000 TON, the tension is 150 KN-240 KN, the cold rolling work roll adopts a rough roll rolling, the cold rolling reduction is 30%-40%, the rolling speed is set to 200-300 m / min, the roll shifting mode is adopted for rolling, and the roll shifting value is 30-90 mm.

[0130] The high dimensional accuracy plate coil production is ensured by roll shifting.

[0131] According to some embodiments of the present application, the second annealing is a bell type furnace annealing.

[0132] According to some embodiments of the present application, the process parameters of the second annealing are as follows:

[0133] The process can guarantee that the material accurately meets the terminal performance requirements, improve the material spheroidization grade and hardness performance, and prevent excessive carbide precipitation, migration and growth, causing surface carbon depletion, and ensure that the material optimizes its machining performance.

[0134] The steel coil is heated from room temperature (20℃-25℃) to 200℃ freely, then heated to 400℃ at a heating rate of 40℃ / h-80℃ / h and kept for 4 hours;

[0135] Then heated to 700℃-800℃ at a heating rate of 40℃ / h-80℃ / h and kept for 10h-20h;

[0136] After the holding is finished, slowly cool to about 600℃, change the air to cool to 400℃, and change the water to cool to 100℃ and discharge.

[0137] The technical effect of the present application is to solve the industry problem of difficult pickling of 9SiCr, large reduction cold rolling production in the form of wide coil plate instead of narrow strip or wide coil plate strip winding after bell type annealing, high production efficiency and low cost. Moreover, in the production of wide plate single stand cold rolling unit, the equipment precision is high and has the roll shifting capability of work roll, which can efficiently and low cost produce high quality cold rolling wide plate coil. Compared with the traditional cold rolling special steel enterprises at home and abroad, the technology can be used to produce cold rolling 9SiCr and other high-end products, which can bring significant economic benefits.

[0138] Example 1

[0139] This example is the production process of 9SiCr wide plate coil with a thickness of 1.8 mm, which consists of the following steps:

[0140] The 9SiCr hot rolled plate coil is subjected to first annealing, pickling, spheroidizing annealing, rolling and second annealing;

[0141] Hot-rolled steel coils of grade 9SiCr were selected as raw materials. The raw material specifications were 3.0mm×1250mm, and the chemical composition was C0.91%, Si1.4%, Mn0.5%, Cr1.1%, with the remainder being Fe and indispensable residual or impurity elements. After cold rolling, the finished product specifications were 1.8mm×1250mm.

[0142] The first annealing is a low-temperature stress-relief annealing with the following parameters:

[0143] The steel coil is heated freely from room temperature (25℃) to 200℃ in half an hour; then heated to 400℃ at a heating rate of 40℃ / h and held for 2 hours; then heated to 650℃ at a heating rate of 70℃ / h and held for 18 hours; after the holding period, it is cooled to 400℃ by air; then cooled to 100℃ by water before being taken out of the furnace and pickled.

[0144] Pickling was performed using hydrochloric acid with a mass concentration of 15% and an acid solution temperature of 82℃; followed by water rinsing at a rinsing temperature of 70℃; the strip steel was then dried with hot air at a temperature of 110℃; and the pickling rate was 120 m / min.

[0145] The pickled steel coils are then subjected to spheroidizing annealing. The parameters for spheroidizing annealing are as follows:

[0146] The temperature is raised from room temperature (25℃) to 200℃ in half an hour; then heated to 400℃ at a rate of 60℃ / h and held for 4 hours; then heated to 790℃ at a rate of 60℃ / h and held for 10 hours; after holding, it is slowly cooled to 600℃; then air-cooled to 400℃; then water-cooled to 100℃ before being rolled out.

[0147] The rolling process is cold rolling, and the process parameters are as follows:

[0148] Cold rolling is carried out using a wide plate single-stand cold rolling mill. The three cold rolling forces are 800TON, 950TON, and 900TON, respectively; the front tensions are 150KN, 180KN, and 240KN, respectively, and the back tensions are 200KN, 240KN, and 280KN, respectively; the cold rolling work rolls are made of rough rolls; the cold rolling reduction is 40%; the rolling speed is 260m / min, and the rolling is carried out using the roll shifting mode, with roll shifting values ​​of 30mm, 30mm, and 0mm, respectively.

[0149] The cold-rolled steel coils are then subjected to bell-type furnace annealing (i.e., second annealing), with the following process parameters:

[0150] The steel coil is heated freely from room temperature (25℃) to 200℃ in half an hour; then heated to 400℃ at a heating rate of 60℃ / h and held for 4 hours; then heated to 750℃ at a heating rate of 60℃ / h and held for 10 hours; after holding, it is slowly cooled to 600℃; then air-cooled to 400℃; and finally water-cooled to 100℃ before being taken out of the furnace.

[0151] After annealing, 9SiCr cold-rolled finished coils of 1.8 mm x 1250 mm (width) specification are produced, with thickness accuracy of ±10 μm, convexity C40 within 6 μm, no oxide residue on the surface of the steel coil, and structure of 5-grade spheroidized pearlite structure. The results after the first annealing, pickling and cold rolling of Example 1 are shown in Table 1. Figures 2 to 4 From Table 1, it can be seen that the surface after cold rolling in this example is smooth and has no residue. Figure 4

[0152] Example 2

[0153] This example is a production process of 9SiCr wide plate coils of 1.5 mm thickness, which consists of the following steps:

[0154] The 9SiCr hot-rolled coils are subjected to the first annealing, pickling, spheroidizing annealing, rolling and second annealing.

[0155] The hot-rolled steel coils of 9SiCr steel are used as raw materials, with a specification of 2.5 mm x 1250 mm, and the chemical composition is C 0.90%, Si 1.3%, Mn 0.4%, Cr 1.2%, and the rest is Fe and indispensable residual or impurity elements. After cold rolling, the finished product specification is 1.5 mm x 1250 mm.

[0156] The first annealing is a low-temperature stress relief annealing, with the following parameters:

[0157] The steel coil is heated to 200°C from room temperature (25°C) in half an hour; then heated to 400°C at a heating rate of 40°C / h and held for 2 h; then heated to 650°C at a rate of 70°C / h and held for 18 h; after the holding is completed, air cooling is performed to 400°C; water cooling is performed to 100°C and the coil is discharged from the furnace, and then pickling is performed.

[0158] The pickling is performed by hydrochloric acid pickling, with a mass concentration of hydrochloric acid of 15% and an acid solution temperature of 82°C; water rinsing is performed at a rinsing temperature of 70°C; the pickled steel strip is dried by hot air, with a hot air temperature of 110°C; and the pickling rate is 120 m / min.

[0159] The pickled steel coil is subjected to spheroidizing annealing, with the following parameters:

[0160] The coil is heated to 200°C from room temperature (25°C) in half an hour; then heated to 400°C at a heating rate of 60°C / h and held for 4 h; then heated to 760°C at a rate of 60°C / h and held for 10 h; after the holding is completed, slow cooling is performed to 600°C; air cooling is performed to 400°C; water cooling is performed to 100°C and the coil is discharged from the furnace, and then rolling is performed.

[0161] The rolling is cold rolling, with the following process parameters:

[0162] ​The cold rolling is produced by a wide plate single stand cold rolling unit, the rolling forces of three passes are 800 TON, 950 TON and 900 TON respectively, the front tensions are 150 KN, 180 KN and 240 KN respectively, the back tensions are 200 KN, 240 KN and 280 KN respectively, the cold rolling work rolls are rough rolls, the cold rolling reduction is 40%, the rolling speed is 260 m / min, the rolls are shifted with a shift value of 30 mm, 30 mm and 0 mm respectively.

[0163] The cold-rolled steel coil is subjected to cover furnace annealing (i.e. the second annealing), and the process parameters are as follows:

[0164] The steel coil is heated from room temperature (25°C) to 200°C freely, then heated to 400°C at a heating rate of 60°C / h and kept for 4 h, then heated to 750°C at a heating rate of 60°C / h and kept for 10 h, then slowly cooled to 600°C, then air cooled to 400°C, then water cooled to 100°C and discharged.

[0165] After annealing, 9SiCr cold-rolled finished coils with a specification of 1.5 mm x 1250 mm (width) are produced, the thickness accuracy is ±7 μm, the crown C40 is within 6 μm. There is no oxide residue on the surface of the steel coil, and the microstructure is 5-grade spheroidized pearlite.

[0166] Comparative Example 1

[0167] This comparative example is the production process of 9SiCr wide plate coils with a thickness of 1.8 mm, and the only difference from Example 1 is that the first annealing is replaced by high temperature annealing, and the parameters of the high temperature annealing are as follows:

[0168] From room temperature (25°C) to 200°C freely in half an hour, then heated to 400°C at a heating rate of 60°C / h and kept for 4 h, then heated to 800°C at a heating rate of 60°C / h and kept for 10 h, then slowly cooled to 600°C, then air cooled to 400°C, then water cooled to 100°C and discharged for pickling.

[0169] The cross section of the steel coil after high temperature annealing (see Comparative Example 1) is shown in Figure 1 The surface oxide is reduced to sponge iron by hydrogen, and it is difficult to remove during pickling.

[0170] After annealing, 9SiCr cold-rolled finished coils with a specification of 1.8 mm x 1250 mm (width) are produced, the thickness accuracy is ±10 μm, the crown C40 is within 6 μm, there are more oxide residues on the surface of the steel coil (see Figure 5 ), and the microstructure is 5-grade spheroidized pearlite. The plate surface quality cannot meet the relevant quality standards.

[0171] To sum up, the production process of the application is different from the existing single stand cold rolling narrow strip rolling mill production of cold rolling 9SiCr, the process flow is more complex, the edge wire cutting loss is large, the production efficiency is low, and the production cost is high; in the application, the 9SiCr hot-rolled plate coil is first subjected to first annealing softening and stress relief, then pickling, then spheroidizing annealing, the annealed steel coil is subjected to rolling, and finally subjected to second annealing to form a cold-rolled finished coil. The application uses wide plate coil to produce high-quality cold-rolled 9SiCr cold-rolled plate coil, which has the characteristics of high production efficiency, low production cost and stable process.

[0172] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the gist of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the elements of the embodiments are also included in the scope of the present application.

Claims

1. A production process for 9SiCr cold-rolled wide sheet coils, characterized in that, Includes the following steps: The 9SiCr hot-rolled coils are subjected to a first annealing, pickling, spheroidizing annealing, rolling, and a second annealing. The first annealing includes a first stage of heating, a second stage of heating, a first stage of holding, a third stage of heating, a second stage of holding, a first stage of cooling, and a second stage of cooling; The temperature of the first stage of heat preservation during the first annealing process is 380℃~420℃; The width of the 9SiCr cold-rolled wide sheet coil is over 900 mm; The final temperature of the first stage of heating during the first annealing process is 190℃~210℃; The spheroidizing annealing includes a first stage of heating, a second stage of heating, a first stage of holding, a third stage of heating, a second stage of holding, a first stage of cooling, a second stage of cooling, and a third stage of cooling; The temperature of the second stage of the spheroidizing annealing process is 700℃~800℃; the heating rate of the first stage of the first annealing process is 350℃ / h-450℃ / h. The first stage of heating during the first annealing process takes 0.4h to 0.6h. The heating rate of the second stage during the first annealing process is 60℃ / h~80℃ / h; The final temperature of the second stage of heating during the first annealing process is 380℃~420℃; The first holding time during the first annealing process is 3 to 5 hours. The heating rate in the third stage during the first annealing process is 60℃ / h~80℃ / h; The final temperature of the third stage of heating during the first annealing process is 500℃~660℃; The temperature of the second stage of heat preservation during the first annealing process is 500℃~660℃; The second stage of heat preservation during the first annealing process is 10h~20h; The final temperature of the first cooling during the first annealing process is 380℃~420℃; The first cooling method during the first annealing process is air cooling; The final temperature of the second cooling during the first annealing process is 90℃~100℃; The second cooling method during the first annealing process is water cooling; The rolling process is carried out using a wide plate single-stand cold rolling mill. The cold rolling force is set to 800TON~1000TON; The tension of the cold rolling mill is 150KN~240KN; The cold rolling work rolls are rolled using rough rolls; Cold rolling reduction: 30%~40%; The rolling speed is 200 m / min to 300 m / min; The rolling process employs a roll shifting method. The value of the eccentric roller is 30mm~90mm.

2. The production process according to claim 1, characterized in that, The pickling solution used for pickling is hydrochloric acid; And / or, the hydrochloric acid has a mass fraction of 12% to 18%; And / or, the temperature of the pickling solution is 70℃~90℃; And / or, the pickling rate is 30 m / min to 160 m / min; And / or, the pickling further includes water washing; And / or, the temperature of the water wash is 60℃~80℃; And / or, the water washing is followed by drying; And / or, the drying is hot air drying; And / or, the temperature of the hot air is 100℃~140℃.

3. The production process according to claim 1, characterized in that, The heating rate in the first stage of the spheroidizing annealing process is 350℃ / h-450℃ / h; And / or, the heating time of the first stage in the spheroidizing annealing process is 0.4h~0.6h; And / or, the final temperature of the first stage of heating during the spheroidizing annealing process is 190℃~210℃; And / or, the heating rate of the second stage during the spheroidizing annealing process is 60℃ / h~80℃ / h; And / or, the final temperature of the second stage of heating during the spheroidizing annealing process is 380℃~420℃; And / or, the temperature of the first stage of heat preservation during the spheroidizing annealing process is 380℃~420℃; And / or, the first stage of heat preservation during the spheroidizing annealing process is 3h~5h; And / or, the heating rate in the third stage of the spheroidizing annealing process is 60℃ / h~80℃ / h; And / or, the final temperature of the third stage of heating during the spheroidizing annealing process is 700℃~800℃; And / or, the second stage of heat preservation during the spheroidizing annealing process is 10h~20h; And / or, the final temperature of the first cooling during the spheroidizing annealing process is 580℃~620℃; And / or, the final temperature of the second cooling during the spheroidizing annealing process is 380℃~420℃; And / or, the second cooling method during the spheroidizing annealing process is air cooling; And / or, the final temperature of the third cooling during the spheroidizing annealing process is 90°C to 100°C; And / or, the third cooling method during the spheroidizing annealing process is water cooling.

4. The production process according to claim 1, characterized in that, The second annealing includes a first stage of heating, a second stage of heating, a first stage of holding, a third stage of heating, a second stage of holding, a first stage of cooling, a second stage of cooling, and a third stage of cooling; And / or, the heating rate of the first stage in the second annealing process is 350℃ / h-450℃ / h; And / or, the heating time of the first stage in the second annealing process is 0.4h~0.6h; And / or, the final temperature of the first stage of heating during the second annealing process is 190℃~210℃; And / or, the heating rate of the second stage during the second annealing process is 40℃ / h~80℃ / h; And / or, the final temperature of the second stage of heating during the second annealing process is 380℃~420℃; And / or, the temperature of the first stage of heat preservation during the second annealing process is 380℃~420℃; And / or, the first stage of heat preservation during the second annealing process is 3h~5h; And / or, the heating rate of the third stage during the second annealing process is 40℃ / h~80℃ / h; And / or, the final temperature of the third stage of heating during the second annealing process is 700℃~800℃; And / or, the temperature of the second stage of heat preservation during the second annealing process is 700℃~800℃; And / or, the second holding time during the second annealing process is 10h~20h; And / or, the final temperature of the first cooling during the second annealing process is 580℃~620℃; And / or, the final temperature of the second cooling during the second annealing process is 380℃~420℃; And / or, the second cooling method during the second annealing process is air cooling; And / or, the final temperature of the third cooling during the second annealing process is 90°C to 100°C; And / or, the third cooling method during the second annealing process is water cooling.

5. The production process according to claim 1, characterized in that, The 9SiCr cold-rolled wide coil is composed of the following elements by mass fraction: C 0.9%~0.95%, Si 1.3%~1.5%, Mn 0.4%~0.6%, Cr 1.0%~1.2% and balance Fe and essential residual or impurity elements.

6. The production process according to claim 1, characterized in that, The thickness of the 9SiCr hot-rolled coil is 2.5mm~3.5mm; And / or, the width of the 9SiCr hot-rolled coil is 900mm~1500mm.

7. The production process according to claim 1, characterized in that, The thickness of the 9SiCr cold-rolled wide sheet coil is 1.5mm~1.8mm; And / or, the width of the 9SiCr cold-rolled wide sheet coil is 900mm~1500mm.

8. The production process according to claim 1, characterized in that, The thickness accuracy of the 9SiCr cold-rolled wide sheet coil is -10μm to 10μm; And / or, the crown C40 of the 9SiCr cold-rolled wide coil is within 6 μm.

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